The present invention relates generally to agricultural implements having a bulk delivery system that supplies product entrained in a forced air flow to multiple on-row hoppers through multiple supply conduits, which may include supply conduits of different lengths, and, more particularly, to a method and apparatus for equalizing distribution of an air/seed mixture to a plurality of on-row hoppers or seed boxes.
Row crop planters typically consist of six or more individual planting or seed units, commonly referred to as “row units”, attached to a tool bar or frame that is towed across a planting surface by a towing vehicle, e.g., tractor. Planters with as many as 36 row units are increasingly common. These row units are either supplied with seed by individual “on-row” hoppers (seed boxes) or by a central system consisting of one or more large tanks. For planters having a central fill system, seed is delivered from the central tank(s) to the individual row units through distribution hoses (runs). Typically, an air delivery system entrains the seed in a forced air stream that is fed to the individual row units. The product is dumped into localized storage tanks for the row units. Each of the localized storage tank has a vented air outlet through which air passes to vent the air to atmosphere. The use of a central tank and distribution network allows for increased seed storage and hence less stops to reload seed. In addition, when refilling is necessary, only the large storage tanks need to be refilled, which also saves stoppage time.
While generally effective, there are some issues with distributing seed or other granular product from a central tank(s) to the individual row units. More particularly, the lengths of the distribution hoses are not the same for each row unit. That is, the length of the distribution hoses increases as the distances from the row units from the central tank(s) increase. As a result, air distribution may be undesirably uneven through runs or distribution hoses of different lengths. While some deviation may be tolerated, too high a differential can lead to plugging on short runs and insufficient product delivery on long runs.
Therefore, there is a need for a product distribution system for use with a planter that is capable of providing greater equalization between distribution hoses or runs of different lengths and as a result, more uniform seed collection by the row units.